1. Field of the Invention
The present invention relates to the field of printed circuit board (PCB). In particular, the present invention is a method for replacing a tape automated bonding (TAB) component on a PCB.
2. Art Background
Traditionally, a TAB component is removed from a PCB by melting the solder applied to the TAB component's leads, and providing a lifting force after the solder has been melted. Typically the solder is composed of approximately 63% Tin and 37% Lead . The solder is melted by applying heat via hot gas or a hot bar. The remaining solder on the solder pads is removed by "wicking" solder away from the solder pads. Typically, the remaining solder is "wicked" using a "solder wick" product having a copper mesh wire with flux. Heat is applied in conjunction with the copper mesh wire to "wick" the remaining solder into the copper braid.
New solder is then applied to the solder pads by melting wire solder and moving a solder iron between the solder pads. Uneven solder is reheated with a sweeping motion using the solder iron until the new solder is uniform. The newly applied solder is allowed to cool below its melting temperature. The replacement TAB component is placed in position with its leads on top of the newly applied solder. Heat is again applied using hot gas or a hot bar to remelt the newly applied solder.
Each step, particularly a heating step, in the removal and replacement process represents an opportunity to damage the PCB. Since the number of components packed in a PCB has increased significantly in recent years, the resultant cost from such damages has also increased significantly. Thus, it is desirable to reduce the number of steps and the cycle time for the steps, particularly the number of heating steps and the heating cycle time. As will be described, the method of the present invention replaces a TAB component with reduced number of steps and cycle time for the steps, thereby reducing the opportunities for damaging the PCB.